Method of installation for a fixed wireless access subscriber antenna

ABSTRACT

This invention relates to radio communication systems and in particular relates to a method of installation for a fixed wireless access subscriber antenna. According to one aspect of the present invention there is provided a method of installing a fixed wireless access arrangement comprising one or more directive antennas operable to be directed at a base station; the method steps comprising: determining the absolute position of the location of the subscribers premises employing a radio position determining receiver; referencing data relating to the absolute position of the location of a fixed wireless access base station; positioning an antenna relative to the base station given the absolute position of the whereby initial set-up of the antenna is sufficiently accurate whereby fine tuning of the antenna is possible. By configuring the antenna mount prior to attachment on the structure, then the time required to deploy fixed wireless access subscriber equipment is much reduced.

FIELD OF THE INVENTION

This invention relates to radio communication systems and in particularrelates to a method of installation for a fixed wireless accesssubscriber antenna.

BACKGROUND TO THE INVENTION

Fixed wireless systems are currently employed for localtelecommunication networks, such as the IONICA fixed radio accesssystem. Known systems comprise an antenna and decoding means which arelocated within a subscriber's premises, for instance adjacent atelephone. The antenna receives the signal and provides a further signalby wire to a decoding means. Thus subscribers are connected to atelecommunications network by a radio link in place of the moretraditional method of copper cable. Such fixed wireless access systemswill be capable of delivering a wide range of access services from POTS,ISDN to broadband data. The radio transceivers at the subscriberspremises communicate with a base station, which provides cellularcoverage over, for example, a 5 km radius in urban environments. Atypical base station will support 500-2000 subscribers. Each basestation is connected to the standard PSTN switch via a conventionaltransmission link/network.

When a fixed wireless access telecommunications system is originallydeployed, then a base station of a particular capacity will be installedto cover a particular area. The capabilities of the base station will becommensurate with the anticipated coverage and capacity requirement.Subscribers antennas will be mounted outside, for instance on a chimneyand upon installation will be directed towards the nearest base stationor repeater antenna (any future reference to a base station shall betaken to include a repeater). In order to meet the capacity demand,within an available frequency band allocation, fixed wireless accesssystems divide a geographic area to be covered into cells. At the centreof each cell is a base station through which the subscribers stationscommunicate; the distance between the cells being determined such thatco-channel interference is maintained at a tolerable level.

Obstacles in a signal path, such as buildings in built-up areas andhills in rural areas, act as signal scatterers and can cause signallingproblems. These scattered signals interact and their resultant signal ata receiving antenna is subject to deep and rapid fading and the signalenvelope often follows a Rayleigh distribution over short distances,especially in heavily cluttered regions. Since the various componentsarrive from different directions, there is also a Doppler spread in thereceived spectrum.

Correct alignment and installation of a fixed wireless access subscriberterminal towards a geographically proximate base station is essentialfor the correct performance of the network. At present, the lack ofsubscriber location precision has resulted in subscribers `firing`across proximate base stations to more distant base stations. Thiscauses a higher level of interference to be experienced than optimumalignment would provide. Presently, as operators of fixed wirelessaccess systems are deploying their equipment into an already crowdedtelecommunications marketplace, to enable them to operate at sufficientcompetitive levels there must be a high rate of deployment ofsubscribers equipment. Obviously, such deployment must not be timeconsuming for installation engineers. Presently, problems have beenexperienced in the installation of subscribers equipment, and moreparticularly, in the mounting of the antennas required to transfer radiosignals with a base station; the subscribers antenna must be orientedtowards the base station to enable the signals to be of sufficientstrength. In particular the installation engineers have reporteddifficulties in determining the location of the subscribers premiseswith respect to a proximate base station, where the techniques employedhave been based on traditional cell planning and data base methods.

OBJECT OF THE INVENTION

The present invention seeks to provide a method and apparatus to improvethe installation of subscribers terminals in fixed wireless accesstelecommunications networks.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided amethod of installing a fixed wireless access arrangement comprising oneor more directive antennas operable to be directed at a base station;the method steps comprising:

determining the absolute position of the location of the subscriberspremises employing a radio position determining receiver;

referencing data relating to the absolute position of the location of afixed wireless access base station;

positioning an antenna relative to the base station given the absoluteposition of the base station. The initial set-up of the antenna issufficiently accurate to communicate radio signals with a base station,since the position can be accurate to within 1° of arc whereby only finetuning of the antenna is necessary.

Preferably, the antenna is mounted on a multi-axis mount, whichmulti-axis mount has scaled gradations, wherein for a known compassorientation of the mount and inclination to the horizontal, can beconfigured, given data relating to the desired angular orientation andthe desired azimuthal orientation of the antenna. Preferably, the radioposition determining receiver is a GPS receiver which determines theposition of the receiver on the earth employing data from satellites inorbit about the earth. Nevertheless other positionning systems such asLoran-C may be employed. In a preferred embodiment, the radio positiondetermining receiver is associated with a portable computer operable toprocess data relating to the desired height and orientation of theantenna, which computer has stored data relating to the absoluteposition of fixed wireless base stations in the area, whereby an antennamount can be oriented with respect to the structure to which the antennawill be positionned. By configuring the antenna mount prior toattachment on the structure, then the time required to deploy fixedwireless access subscriber equipment is much reduced.

In another aspect of the invention there is provided an antenna mountcomprising:

a first member suitable for attachment to a structure, having a portionsuitable for attachment to a structure and a portion for attachment toan articulated member associated with the antenna body;

a second member for attachment to the antenna and the first member;

wherein there is a jointed portion which connects the first and secondmembers and can adjustably determine the orientation of the antenna withrespect to the structure whereby the antenna is maintained in an optimumposition to exchange radio signals with a fixed wireless access basestation.

In accordance with a still further aspect of the invention there isprovided an antenna mount comprising:

a first member suitable for attachment to a structure, having a portionsuitable for attachment to a structure and a portion for attachment toan articulated member associated with the antenna body;

a second member for attachment to the first member and to a thirdmember;

wherein there is a jointed portion which connects the first and secondmembers which can adjustably determine the orientation of the secondmember with respect to the structure;

a third member for attachment to the antenna and the second member;wherein there is a jointed portion which connects the second member andthe antenna and can adjustably determine the orientation of the antennawith respect to the second member;

whereby the antenna is maintained in an optimum position to exchangeradio signals with a fixed wireless access base station.

Preferably the jointed portions have scaled gradations, whereby theantenna orientation can be easily configured. The jointed portion mayhave a ball joint coupling arrangement. Alternatively, the jointedportions may be movable in only one angular orientation. The secondmember may have a rotatable portion such that the angular variation neednot be either horizontal or vertical for instances when the first membercannot be positionned such that the azimuthal or elevational adjustmentis not precisely such. Alternatively the first member has a rotatableportion whereby the azimuthal or elevational adjustment of the jointedportion is horizontal or vertical, respectively, as required. A stillfurther advantage is that there is no need to know the precise locationof subscriber in order to identify candidate base stations prior to asite visit. At present it is required to locate the potential subscriberon a map (latitude and longitude) then access data base for coverage.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present invention is more fully understood, referenceshall now be made to the Figures as shown in the accompanying drawingsheets, wherein:

FIG. 1 is a diagrammatic perspective view of a typical installation of afixed wireless access subscriber antenna assembly, as is known;

FIG. 2 shows an arrangement in accordance with the invention;

FIG. 3 shows the arrangement of FIG. 2 deployed in a cellular network;

FIGS. 4a and 4b show examples of sources of fading;

FIG. 5 details a mount for the antenna; and

Appendix 1 shows a flow diagram of the installation operation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The integrated antenna assembly 10 shown in FIG. 1 comprises one part ofa residential service system for a fixed wireless access arrangement andis mounted on a chimney breast 12 of a house--it is preferably locatedbetween fascia board level and 1-2 m above the roof top. In this case,the antenna assembly is mounted for use in a fixed wireless access(wireless local loop) telecommunications environment and is connectedvia a cable 14 to a junction unit for connection with standard telephoneand/or facsimile equipment and a power unit.

Referring now to FIG. 2, there is depicted a first embodiment of theinvention, wherein the subscriber unit comprises an antenna 22 which ismounted on a support body 24 and is operable to transmit radio signalsto and receive radio signals from a base station. The antenna can bedirected at one or more base station antennas, depending upon the localterrain and disposition of base stations. The best received signal canaccordingly be used to determine the orientation of the antenna insubsequent communications. Alternatively, the base station providing thebest signal may have reached its system capacity limit and the basestation providing the next best signal may be employed.

The provision of a simple method of alignment of such an antenna withrespect to a base station antenna provides the capability for someadaptive reconfiguration of the wireless local loop network, whichallows maximum advantage to be taken of base station selection. FIG. 3shows a simplified representation of a fixed radio access base stationnetwork: a subscribers premises 30 has an antenna installation 32 whichenables the subscriber unit the choice of communicating with a number ofadjacent base stations 34.

Upon installation, the antenna is directed towards the nearest basestation. If a building is erected such that it interferes with anoptimal link with this base station, then this link may not besufficiently strong to provide an effective link. At such times thealignment of the antenna would have to be adjusted in a similar fashionas occurred upon the original installation of the antenna whereby theantenna can achieve an optimal link. Since the antenna can communicatewith any base station within range, fixed obstructions due to terrainfeatures--see FIG. 4a and terrain clutter such as buildings, trees andthe like, can be taken into account during installation. Duringdeployment of base stations an accurate position fix is generally takeneither based on maps or a positioning system such as the GlobalPositioning System (GPS). A record of all base stations (and basestation identifiers--Bids) is kept and is retained on a database.Alternatively, a fix could be obtained using the base stations of thefixed wireless access arrangement to triangulte the position of thesubscribers premises.

When visiting a site to install a new subscriber a computing device(e.g. a Personal Computer) in combination with a position finding device(e.g. a GPS receiver) is used to establish the closest base station(s)and display a compass bearing. A compass (or direction finding device)is then used to locate the base station signal directions. An assessmentof the signal from the geographically closest base stations can then beperformed. A signal measuring device which may use any antenna type canbe used to establish the lowest path loss base station--in general thiswill be the preferred base station. If a directional antenna (preferred)is used any angular multi-path can be recorded (signal power from areflection arriving at the site from outside the direct path) and it canbe verified that the subscriber antenna is aligned with a direct radiopath (rather than an angular reflection). By employing a compass in thedetermination of the direction of the base station, the installer can besure that the signal is a direct signal from the base station ratherthan multi-path. At present strongest signal could be a multi-path thatis likely to change more rapidly than a direct path.

Once a base station has been selected, using position and height data ofthe base station and the position, height and orientation data of theparticular mount for the antenna, an antenna mount is attached to thesubscriber's residence. The mount is an adjustable mount. FIG. 5 showviews of a first type of mount 500 comprising a first member 502 whichpossesses fastening means such as screw holes 504 for fastening usingscrews or bolts to be passed through into masonry, timber or the likeassociated with the subscribers premises 506. Using a compass, magneticnorth can be determined and its position noted relative to a gradedscale 508 for the azimuthal positionning of the antenna and from whichthe installation engineer can determine the correct azimuth orientationfor the antenna. Associated with an elevation pivot 512 is a furthergraded scale 514 which is employed for the correct determination of theangular elevation of the antenna. In this embodiment, the first member502 is connected to an intermediate member 516, which intermediatemember is connected to a member 518 associated with, or, is an integralpart of the antenna. The connection of the first member with theintermediate member defines the azimuthal orientation of the antennawhilst the connection between the intermediate member and the thirdmember determines the elevational orientation of the antenna. Therelative functions between the members could be interchanged, but it isbelieved that it is easier to determine the required level horizontaldisposition of the mount and hence the azimuthal orientation.Alternatively, the mount can comprise two members with a lockable balljoint connecting the two.

By referencing the antenna mount to magnetic north the data can be usedin the determination of the correct angular dispositions of the mountingelements relative to one another and the antenna. With the use of such amount, upon the fixing of the first element to the wall, the rest of themount can be assembled at ground level rather than up on a rooftop orsimilar, with the correct angular orientations being determined from thecomputer taking into account the radio positionning system details andthe particular details about the subscribers premises such as the heightof the intended placement, the general azimuthal field of view of theantenna etc. Once an antenna has been positionned, because of theaccuracy of typical radio positionning devices being of the order oftens of meters, adjustment may be made with the assistance of micrometeradjusters, for final, optimum coupling of signals. A meter may beemployed to determine the greatest received signal level in conjunctionwith the micrometer screw adjustment means.

Referring to Appendix 1, there is shown a flow chart which describes theinstallation procedure. Using a radio positionning system, such as a GPSlocating system, the person carrying out the installation determines theexact co-ordinates of the site, including the proposed height of a mountfor the antenna. The data so obtained is entered into a computer whichhas knowledge of the base stations in the vicinity, taking into accountthe possibility, for example, that the antenna will only be able to facea particular direction within a particular angular spread. The mount forthe antenna is then installed, with a reference to magnetic north orsome other reference point.

Taking into account the desired azimuth and elevational angles, themount can be adjusted so that the antenna sits in primarily the correctorientation, which will require only small adjustment using, forexample, micrometer screws with the use of a peak signal detector foroptimum alignment. Redirecting the antenna would be necessary, forexample, if the capacity load of the first base station is exceeded, orif it requires maintenance or upgrading, or if as previously discussed,the link with the existing base station becomes unsatisfactory. The useof the multidirectional mounting bracket will be of great benefit insuch circumstances, whereby the antenna can be repositionned withrespect to the azimuth and elevational gradations.

The performance of present and other presently envisaged wireless localloop or fixed radio access systems will be compromised at high microwaveand millimetric frequencies due to the effects of slow temporal fading.At such high frequencies, diffraction into shadowed regions becomes lesssignificant and therefore very high transmit powers are required. Topenetrate shadowed regions. As such, the use of high frequencies isuntenable. In contrast, the present invention allows a subscriber to useflexibly any one of a number of base stations which is within range.

Temporally varying slow fades due to building construction, treesgrowing and gaining leaves can, however, cause problems. FIG. 4b showsexamples of such sources of fading. Further problems would also arisedue to increases in the numbers of subscribers and the effects of cellsplitting, as a result of the provision of further base stations.Present systems would require that an installation man would need to bedeployed to realign subscribers antennas as new base stations aredeployed or as temporal fades occur. If the absolute position of asubscribers antenna is known, then the time required for realignment andthe overall network maintenance costs are considerably reduced.

In the case of a particular base station being at its capacity limit andfor traffic reasons the new antenna should not be connected to such abase station, then that base station could provide an amended broadcastcontrol message to prevent attachment to them.

The data base for the calculating means which determines the position ofthe most proximate base stations may be remote and a means provided forcommunication between the remote computer and the data base (e.g. amobile phone or even using the fixed wireless access system itself).

APPENDIX 1 STEP 1

Obtain base station co-ordinates;

STEP 2

Obtain co-ordinates of location where subscribers antenna is to beinstalled employing radio frequency positionning system;

STEP 3

Determine proposed height of antenna from ground;

STEP 4

Determine angular field of view of antenna;

STEP 5

Determine co-ordinates of proximate line of sight base stations;

STEP 6

Select base station taking into account terrain and capacity of basestation;

STEP 7

Determine angle of azimuth and angle of elevation of antenna withrespect to the antenna;

STEP 8

Place first mounting member on subscribers premises, ensuring that areference point associated with first member of mount is determined;

STEP 9

Adjusting the angle of elevation of the second member with respect tothe third member of the mount given data from co-ordinate calculatormeans;

STEP 10

Place second member of mount onto first member of mount (now attached tosubscriber premises) and ensuring the angular orientation in azimuth iscorrect;

STEP 11

Using a peak signal detector attached to antenna, adjust orientation ofantenna to maximise output of received control channel signals andsecuring antenna when complete.

What is claimed is:
 1. A method of installing a fixed wireless accessarrangement at a subscriber's premises comprising a directive antennaoperable to communicate with a base station the fixed wireless accessarrangement comprising; a fixed wireless access subscriber antennamount, an antenna having a body portion and a transmit/receive portion,the mount comprising; a first member suitable for attachment to astructure, having a portion suitable for attachment to the structure anda portion for attachment to an articulated member associated with theantenna body portion; a second member for attachment to the antenna andthe first member; wherein there is a jointed portion which connects thefirst and second members and for adjustably determining the orientationof the antenna with respect to the structure whereby the antennatransmit/receive portion can be positioned in an optimum position toexchange radio signals with a fixed wireless access base station;themethod steps comprising:determining the absolute position of thesubscribers premises by employing a GPS receiver; determining therelative position of the subscribers premises relative to the absoluteposition of the fixed wireless access base station; determining therequired azimuthal and elevation orientation data of the subscribersantenna relative to the absolute position of a fixed wireless accessbase station; and, directing the subscribers antenna relative to thebase station employing the azimuthal and elevation orientation data. 2.A method according to claim 1 wherein the radio position determiningreceiver is associated with a portable computer operable to process datarelating to the desired height and orientation of the antenna, whichcomputer has stored data relating to the absolute position of fixedwireless base stations in the area; whereby an antenna mount can beoriented with respect to the structure to which the antenna will bepositionned.
 3. A fixed wireless access arrangement comprising; a fixedwireless access subscriber antenna mount, an antenna having a bodyportion and a transmit/receive portion, the mount comprising;a firstmember suitable for attachment to a structure, having a portion suitablefor attachment to the structure and a portion for attachment to anarticulated member associated with the antenna body portion; a secondmember for attachment to the antenna and the first member; wherein thereis a jointed portion which connects the first and second members and foradjustably determining the orientation of the antenna with respect tothe structure whereby the antenna transmit/receive portion is maintainedin an optimum position to exchange radio signals with a fixed wirelessaccess base station.
 4. A fixed wireless access arrangement according toclaim 3; wherein the jointed portion has scaled gradations, whereby theantenna orientation can be easily configured.
 5. A fixed wireless accessarrangement according to claim 3; wherein the jointed portion comprisesco-operating ball and socket joint portions.
 6. A fixed wireless accessarrangement according to claim 3; wherein said first member has arotatable portion such that the angular disposition of one end relativeto the other end may be rotated.
 7. A fixed wireless access arrangementaccording to claim 3; wherein said second member has a rotatable portionsuch that the angular disposition of one end relative to the other endmay be rotated.
 8. An antenna mount for a fixed wireless accesssubscriber, the mount comprising:an antenna having a body portion; afirst member suitable for attachment to a structure, having a portionsuitable for attachment to the structure and a portion for attachment toan articulated member associated with the antenna body portion; a secondmember for attachment to the first member and to a third member; whereinthere is a jointed portion which connects the first and second memberswhich can adjustably determine the orientation of the second member withrespect to the structure; the third member being for attachment to theantenna and the second member; wherein there is a jointed portion whichconnects the second member and the antenna and adjustably determines theorientation of the antenna with respect to the second member; wherebythe antenna is maintained in an optimum position to exchange radiosignals with a fixed wireless access base station.
 9. An antenna mountaccording to claim 8; wherein the jointed portions have scaledgradations, whereby the antenna orientation can be easily configured.10. An antenna mount according to claim 8; wherein the jointed portionscomprise co-operating ball and socket joint portions.
 11. An antennamount according to claim 8; wherein the jointed portions are pivotablyin only one angular orientation.
 12. An antenna mount according to claim8; wherein said first member has a rotatable portion such that theangular disposition of one end relative to the other end may be rotated.13. An antenna mount according to claim 8; wherein said second memberhas a rotatable portion such that the angular disposition of one endrelative to the other end may be rotated.